It has been proposed to provide a plastic closure for a container, which includes a plastic cap or shell with an interior liner for sealing engagement with a sealing surface of the container neck finish. For example, U.S. Pat. No. 4,984,703 discloses a plastic closure that comprises a shell having a base wall with a peripheral skirt and an internal thread for securing the closure to a container neck finish, and a sealing liner compression molded in situ on the interior of the shell base wall. U.S. Pat. No. 5,451,360 discloses a method and apparatus for compression molding the liner in situ within the closure shell. It also has been proposed to provide plastic resin barrier materials within the sealing liner for resisting transmission of gases (e.g., carbon dioxide and oxygen), water vapor and/or flavorants through the liner. For example, U.S. Pat. No. 6,371,318 discloses a plastic closure and method of manufacture in which a liner is compression molded in situ on the interior surface of the closure base wall, and includes a multiplicity of alternating layers of matrix polymer such as EVA and barrier polymer such as EVOH. U.S. Pat. No. 6,399,170 discloses a plastic closure and method of manufacture in which the liner is compression molded in situ on the interior surface of the closure base wall and includes a dispersion of barrier polymer platelets, such as EVOH, dispersed within matrix polymer such as EVA.
It is desirable to provide a closure and liner construction, a method of closure manufacture, and a closure and container package that are particularly well adapted for high-temperature applications. Such high-temperature applications include, for example, so-called hot-fill applications in which the container is filled with product while the product is hot. High-temperature applications also include applications in which the filled package is subjected to pasteurization or retort after filling. During retort applications, for example, the filled package may be subjected to a temperature of 265° F. for fifteen minutes. High-temperature situations also can occur when a package is filled with a carbonated beverage and subjected to storage under high-temperature conditions, in which the internal pressure within the container can increase dramatically. In all of such high-temperature situations, the container closure is subjected to elevated internal pressure that tends to distort or dome the closure base wall and lift the sealing liner away from sealing engagement with the container neck finish.
U.S. Patent Document 2003/0098286 discloses a plastic closure that has particular utility for such high temperature applications. The closure includes a shell having a base wall and a skirt with one or more internal thread segments for securing the closure to a container neck finish. In some embodiments, a plastic disk is loosely captured within the closure shell. An annular ring extends axially from the disk adjacent to but spaced from the periphery of the disk. A resilient liner is molded onto the disk over at least the central portion of the disk and over the ring on the disk. The ring urges the liner into sealing engagement with the radially inner edge and the axial end of the container neck finish when the closure is secured to the container finish. In some embodiments of the closure disclosed in the noted patent document, the disk includes an annular rib around the periphery of the disk, with the liner extending around the inner periphery of the rib. The disk in these embodiments thus urges the liner into sealing engagement with the inner and outer edges of the container neck finish as well as the axial end of the container neck finish. When a filled package that includes such a closure is subjected to elevated temperatures, during retort applications for example, the liner is maintained in sealing contact with the container finish.
Although the closure, package and method of manufacture disclosed in the noted patent document address and overcome problems theretofore extant in the art, further improvements remain desirable. In particular, in embodiments in which the liner is disposed on a separate disk retained within the closure shell, there are concerns associated with potential accumulation of debris and/or liquid product in the space between the disk and the base wall of the closure shell and/or between the closure skirt and the container finish, which can promote growth of mold or other undesirable matter. It therefore is a general object of the present disclosure to provide a closure, a closure and container package, and a method of manufacture that include facility for flushing the area between the closure shell and the liner disk and/or between the closure skirt and the container neck finish after the closure has been assembled to the container.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A plastic closure in accordance with one aspect of the present disclosure includes a plastic closure shell having a base wall with a central opening, a skirt for securing the closure to a container neck finish, and an internal ledge on the skirt adjacent to but spaced from the base wall. A plastic disk is retained within the closure shell. The disk includes a plurality of axially extending spacer elements, preferably in the form of angularly spaced circumferentially aligned bead segments around a peripheral portion of the disk, to engage an underside of the base wall and space the disk from the base wall of the shell. Angular gaps between the spacer elements permit flow of fluid from the central opening, between the base wall and the disk and through the gaps. A periphery of the disk is disposed between the internal ledge on the skirt and the base wall of the shell to capture the disk such that the disk is free to rotate within the shell. A resilient sealing liner is molded on an underside of the disk for sealing engagement with the container neck finish. The internal ledge on the skirt preferably includes at least one radially inwardly opening axially extending drain slot to permit flow of fluid around the periphery of the disk and through the slot in the ledge.
A closure and container package in accordance with another aspect of the present disclosure includes a container having a neck finish and a plastic closure secured to the container neck finish. A method of making a closure and container package in accordance with yet another aspect of the present disclosure includes providing a glass or plastic container having a neck finish with at least one external thread segment, and a closure that includes a shell with a skirt having at least one internal thread segment. The closure shell has a base wall with a central opening, and a disk is retained within the shell parallel to but separate from the base wall of the closure. The disk includes a plurality of angularly spaced axially extending spacer elements around the disk in abutting engagement with the base wall of the closure shell spacing the disk from the base wall. Angular gaps between the spacer elements permit flow of fluid from the central opening, between the base wall and the disk, through the gaps and around the edge of the disk. The disk has a periphery disposed between the base wall and an internal ledge on the skirt of the closure shell to capture the disk within the said shell such that the disk is free to rotate within the shell. A resilient liner is molded onto an underside of the disk for sealing engagement with the container neck finish. The container is filled with a fluid product, and the closure is secured to the container with the liner in sealing engagement with the neck finish. The closure is then flushed by directing fluid into the base wall opening, between the base wall and the disk, through the gaps between the spacer elements, and then past the periphery of the disk between the skirt and the neck finish.